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Using metal foam as a flow field structure is an attractive route to improve the performance of open-cathode PEMFC. Metal foam has shown great potential in improving the uniformity of reactants, but optimized structure parameters that can more effectively transfer gas and remove excess water are needed. Here we experimentally investigate the effect of metal foam structure parameters on cell performance using polarization curves, power density curves, and electrochemical impedance spectrum (EIS) measurements. By optimizing the pore density, thickness, and compression ratio of the metal foam, the performance of the fuel cell is improved by 49.8%, 42.1%, and 7.3%, respectively. The optimum structure value of metal foam is the pore density of 40 PPI, the thickness of 2.4 mm, and the compression ratio of 4:2.4. In this configuration, the cell could achieve a maximum power density of 0.485 W cm−2. The findings of this work are beneficial for the application of metal foams in open-cathode PEMFC. [ABSTRACT FROM AUTHOR]

Lithium-based battery packs consist of numerous battery cells which form an essential component of electric vehicles. Inadequate heat transfer creates various challenges to safety issues in these batteries. Hence, assessment of the thermal performance of battery packs is an integral part of the design phase. In this study, a numerical approach of the system is implemented using a three-dimensional cylindrical model of a lithium Manganese dioxide battery cell. The model incorporates the application of the metal foam of different geometrical parameters saturated with air for the thermal cooling of batteries. The model considers the cooling phenomenon during discharge process of a cell with a C-rate of 1C respectively. The change in internal resistance of the cell with temperature during the process is estimated using the Generalized Reduced Gradient (GRG) algorithm. The system is considered to be adiabatic by maintaining a flow of liquid through convective tubes, to maintain a constant temperature. The Battery Thermal Management System design is proposed using the Ansys-Fluent software assuming finite volume analysis. The results are analyzed in terms of the maximum battery temperature attained and with the maximum surface temperature of the battery and the metal foams acquired during the process. [ABSTRACT FROM AUTHOR]

Dissipation of heat has become a common reason for the thermal runway and malfunction of various electronic devices. To effectively use these devices, it is mandatory to extract heat from the dissipating parts. Impinging jet flows (IJF) have been used for cooling purposes for decades. The jet impingement technique contains a pressurized fluid and is designed to spray the fluid with the help of a nozzle on the surface of the disc or plate which is being heated. However, recent advances on the effective heat transfer using metal foams are being studied. This research work focuses on the contribution of laminar and turbulent flows from IJF in extracting heat from the surface plate in the presence of geometrically diverse metal foams. The factors under consideration are H/Dj, Heat flux, thickness of the metal foams, and diameter of the metal foams. This research is purely experimental, and the experimental setup consists of mainly compressor, pressure gauges, rotameter, electric resistor, and thermocouples. The flows are controlled through rotameter and are kept in the range of Re from 800 to 2000 for laminar and from 3000 to 23000 for turbulent region. The outcomes of the results are extremely useful in engineering applications and the data can be used to design an effective heat exchanger. [ABSTRACT FROM AUTHOR]

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In this work, theoretical and numerical studies of the dynamic response of a fiber–metal laminate (FML) sandwich beam under uniform blast loading are conducted. On the basis of a modified rigid-plastic material model, the analytical solutions for the maximum deflection and the structural response time of FML sandwich beams with metal foam core are obtained. Finite element analysis is carried out by using ABAQUS software, and the numerical simulations corroborate the analytical predictions effectively. The study further examines the impact of the metal volume fraction, the metal strength factor between the metal layer and the composite material layer, the foam strength factor of the metal foam core to the composite material layer, and the foam density factor on the structural response. Findings reveal that these parameters influence the dynamic response of fiber–metal laminate (FML) sandwich beams to varying degrees. The developed analytical model demonstrates its capability to accurately forecast the dynamic behavior of fiber–metal laminate (FML) sandwich beams under uniform blast loading. The theoretical model in this article is a simplified model and cannot consider details such as damage, debonding, and the influence of layer angles in experiments. It is necessary to establish a refined theoretical model that can consider the microstructure and failure of composite materials in the future. [ABSTRACT FROM AUTHOR]

Metallic foams exhibit unique properties that make them suitable for diverse engineering applications. Accurate mechanical characterization is essential for assessing their performance under both monotonic and cyclic loading conditions. However, despite the advancements, the understanding of cyclic load responses in metallic foams has been limited. This study aims to propose a mesostructural model to assess the fatigue behavior of open-cell metal foams subjected to cyclic loading conditions. The proposed model considers the previous load history and is based on the analogy of progressive collapse, integrating a finite element model, a fatigue analysis model, an equivalent number of cycles model, and a failure criterion model. Validation against experimental data shows that the proposed model can reliably predict the fatigue life of the metallic foams for specific strain amplitudes. [ABSTRACT FROM AUTHOR]

The main task of this work is the optimization of the manufacturing process of Al-alloy lattice cellular structures with rhombic cell, obtained with lost-PLA technique. It is an easy, environment sustainable and economical technique (both for infrastructure and operating costs) for the manufacturing of Al porous structure based on the 3D printing of PLA and replication process alternative to that based on expensive metal 3D printers. Plaster processing, PLA burnout and AA 6082 alloy casting conditions and parameters have been suitably tuned in order to get final samples with geometry and surface finishing conditions identical to the starting ones made in PLA. A good replication process has been implemented with a high repeatability rate and accurate surface finishing, comparable with that of the PLA printed objects. Morphological analysis on PLA and Al 6082 was conducted as well microstructural analysis and Vickers microhardness tests on Al alloy samples in the as-cast conditions. Metallography reveals the presence of AlFeSi and AlFeMnSi intermetallic phases at the cell boundaries and some coarse precipitates Mg2Si in the AA 6082 alloy. Microstructures and HV measured values are aligned with literature data for this alloy in the same (as-cast) conditions. [ABSTRACT FROM AUTHOR]

The need for high speed and reduction in size in electronic components leads to a rise in the power dissipation needed for thermal management. In this research, experiments have been carried out to examine the thermal efficiency from heat sink located on an energy source in a channel. A total of 4 test models with different shapes were tested. Model 1 conventional heat sinks is made from aluminum, model 2 fin heat sinks is made from metal foam, model 3 plate heat sink is made from metal foam and model 4 fin heat sinks filled space between the fins with metal foam; all models have the same flat plate surface area. Copper metal foam of constant pore density of 40 PPI and constant porosity of 0.91 were used. The test runs are done at the air flow rates ranging between (1.2 to 3.3) m/s with the inlet air temperature is 27 °C. The outcomes revealed that the model 3 heat sinks have a greater heat transfer coefficient and a lower thermal resistance than the other types of heatsinks. At input velocity of 3.3 m/s and high power of 30 W, model 3 has the best Nusselt number ratio it has increased from models 2 and 4 by 13.7% and 6.8%, respectively. The plate foam heat sink model 3 has a larger pressure drop when compared to conventional fin heat sink model 1. Moreover, the pressure drop between Models 2 and Model 4 is not significantly different. Additionally, at higher flow rates, the model 3 heat sinks show a 22% reduction in thermal resistance compared to the model 1 at a power of 30 W. [ABSTRACT FROM AUTHOR]

The main task of this work is the optimization of the manufacturing process of Al-alloy lattice cellular structures with rhombic cell, obtained with lost-PLA technique. It is an easy, environment sustainable and economical technique (both for infrastructure and operating costs) for the manufacturing of Al porous structure based on the 3D printing of PLA and replication process alternative to that based on expensive metal 3D printers. Plaster processing, PLA burnout and AA 6082 alloy casting conditions and parameters have been suitably tuned in order to get final samples with geometry and surface finishing conditions identical to the starting ones made in PLA. A good replication process has been implemented with a high repeatability rate and accurate surface finishing, comparable with that of the PLA printed objects. Morphological analysis on PLA and Al 6082 was conducted as well microstructural analysis and Vickers microhardness tests on Al alloy samples in the as-cast conditions. Metallography reveals the presence of AlFeSi and AlFeMnSi intermetallic phases at the cell boundaries and some coarse precipitates Mg2Si in the AA 6082 alloy. Microstructures and HV measured values are aligned with literature data for this alloy in the same (as-cast) conditions.

The two-dimensional numerical simulations focused on fluid flow and heat transfer within a solar air heater (SAH) channel incorporating copper metal foam with a porosity of 90% were carried out in this study. The Local Thermal Non-equilibrium (LTNE) and Darcy-Extended Forchheimer (DEF) models were employed to predict fluid and thermal transport in the partially porous SAH channel. In the free flow zone, the turbulence model was utilized. The thermal and thermo-hydraulic performances of SAH were examined concerning several factors, including pore density ( ), Reynolds number ( ), and dimensionless foam height ( ). The results demonstrate that inserting a porous substrate into the SAH can substantially increase heat transmission. This enhancement ranges from 4.4 to 18.04 times compared to an empty duct for at . Moreover, increased porous layer height and pore density lead to a corresponding increase in pressure drop. Evaluating both the improvement in heat transmission and the associated pressure penalty, the case with , and demonstrate superior overall performance, boasting a higher Thermal Performance Factor ( ) of 2.82 when compared to an empty channel. This work presents significant findings on optimizing metal foam applications in SAH systems, offering new insights into the field.

High output temperature and photothermal conversion effectiveness were achieved with the absorber platform structure. A novel solar receiver was manufactured to integrate pre-heating and thermal conversion, aiming to enhance heat utilization and output temperature. This work is based on the engineering design and experimental testing of a solar cavity-receiver containing a porous copper foam that can volumetrically absorb high-flux radiation and heat up, through convection with air-flow. The air outlet temperature, outer wall temperature, thermal performance, and efficiency were experimentally determined by pore density, air mass-flow rate and solar irradiance. Additionally, the temperature growth of unit incident power, the unit volume efficiency growth rate, and output temperature were employed to evaluate the thermal conversion characteristics of the endothermic body (copper foam). The results indicated that the air outlet temperatures can reach 500 °C with lower input power. Furthermore, it was found that under a pore density of 30 pores per inch and a flow rate of 60 Lpm, the photothermal conversion efficiency of the absorber with copper foam reached as high as 87.61%, which is 35.04% significantly higher than that of an absorber without copper foam. The manageable solar receiver design proved to deliver a high-temperature air-flow (approximately 500 °C) with a reasonably high thermal efficiency (over 85%). [ABSTRACT FROM AUTHOR]

Porous copper (Cu), with varying porosities, has been made using carbamide as a space holder through the powder metallurgy route. Two shapes of carbamide particles were used, (i) needlelike and (ii) spherical, in order to investigate the effect of the space holder shape on the pore structure and mechanical properties of porous Cu. The compressive deformation behavior of porous Cu was studied under a compression test. The pores' structural characteristics and mechanical properties of the porous Cu varied significantly with the shape of the space holder. Although the effect of the space holder shape on the porosity was not regular, the effect on the mechanical properties was regular. The stress increased monotonically with the increase in the strain, and strain hardening occurred at the plastic yield stage. The elastic modulus and yield strength followed the power law, with the relative density irrespective of the space holder shape. The empirical constants associated with different empirically developed power law relations were different, according to the shape of space holder. A quantitative relationship between the elastic modulus and yield strength and the spacer content was obtained to control the mechanical properties of the present porous Cu or other porous metals and metal foams using the well-known space holder method. [ABSTRACT FROM AUTHOR]

This study investigates the impact of gas flow field design on the performance of a solid oxide fuel cell (SOFC). A three-dimensional numerical model of the cell and channel is developed to simulate the use of metal foam as flow distributor, along with the presence of obstacles in the gas flow channels. The model is calibrated using experimental data and applied to simulate four relevant cases combining metal foam and obstacles, compared to a straight channel structure. The results demonstrate the positive impact of flow-field modifications on the distribution of species along the cell's active layers. It is found that, even though the pressure drops are affected, reactant gases are more uniformly distributed across the active electrode of the cell, reducing mass transport losses and enhancing current density. Simulations performed at a cell voltage of 0.7 V indicate that incorporating a metal foam as flow distributor increases the maximum current density by 26 % compared to the conventional straight flow design. Furthermore, combining metal foam with obstacles results in the best performance, achieving a 34 % increase in the maximum current density.

The aim of the present research work is to understand the intricacies of fluid flow through a rectangular channel that has been partially filled with a metal foam block of different blockage ratio (0.16-1), with a pore density (5-30 Pores Per Inch i.e. PPI), along with varying inlet velocity (6.5-12.5 m/s). For the porous region, numerical solutions are acquired using the Darcy Extended Forchheimer model. The Navier-Stokes equation is used in the non-porous zone. Different flow behaviours were seen as a function of PPI, height, and inlet velocity. The pressure drop increases with inlet velocity, PPI, and block height, with a maximum value of approximately 4.5 kPa for the case of 30 PPI, 12.5 m/s, and a blockage ratio of 1. Results show that the existence and location of the formation of eddies depends on the inlet velocity, PPI, and blockage ratio. Such studies have been reported less and will aid research on forced convection through a channel partially filled with metal foam and optimisation studies between increased heat transmission and the additional pressure drop for the same by providing a detailed fluid flow analysis. [ABSTRACT FROM AUTHOR]

Protective steel doors are widely used in buildings due to their high resistance against the impact loads. However, its heavy weight has been always considered as a major drawback for these doors. In this paper, a new optimized stiffened impact-protective steel door incorporating sandwich panel with aluminum foam core (OSSA) is examined. This door consists of two face sheets, main and secondary stiffeners, and aluminum foam as the inner core. In order to optimize the door, at first the rigidity and weight functions of the stiffened steel door were extracted. Then an optimal door weighing 42% less than the primary door was obtained. Due to the high energy absorption capacity of the combined foam core and stiffened steel door structure, the use of aluminum foam core in the optimized steel door was proposed. By doing numerical analysis, and depending on the thickness of the face sheet of OSSA, 20 to 32% reduction in the maximum displacement was observed. The results also showed that, with 67% increase in the peak overpressure, OSSA has kept almost the same maximum displacement as that of the steel door without an aluminum foam. In other words, by using aluminum foam core in the optimized stiffened door, the door will resist 67% more impact load. [ABSTRACT FROM AUTHOR]

With the development of surface engineering, porous surfaces have emerged as a significant research subject in boiling heat transfer. The latter, in turn, plays a crucial role in various industries such as power plants, distillation plants, and microelectronic technology. In this paper, the Molecular Dynamics method is adopted to investigate the wicking dynamics and boiling dynamics of two porous surfaces: foam, which exhibits randomly distributed pores, and mesh, composed of ordered square wires with relatively uniform pore sizes. Three wettability, namely hydrophilic, neutral, and hydrophobic wetting states, are assigned to the two porous surfaces de-coupling the effect of wettability from surface structure. Results reveal that, during the wicking process, the foam surface shows better wetting ability as it absorbs liquid under both hydrophilic and neutral wettability. Comparatively, the mesh surface has the fastest wicking speed under hydrophilic wettability yet it becomes non-wetting under neutral wettability. During the boiling process, the boiling dynamics differ greatly under three wettability. More importantly, the difference in surface structure makes the foam surface possess a better heat transfer whereas the mesh surface causes gentle pressure variation. Our findings provide insights into the design of artificial porous surfaces for certain purpose and their potential application.

A 2D numerical analysis was conducted to examine the melting performance of a shell-and-tube-type phase change material with a two-layer copper foam having higher and lower porosity levels. The design parameters for these two layers of metal foam consisted of three different volume fill ratios (VFR) (30 %/70 %, 50 %/50 %, and 70 %/30 %) and three different shapes (circular, semi-circular, and elliptical) for the lower porosity layer. The results showed that a semicircular-shaped low porosity layer with a 30 % VFR had the least melting time of 475 s. When the VFR increased to 50 %, the elliptical and circular shapes had the least melting time of 394 s. However, at a VFR of 70 %, only the elliptical shape had the least melting time of 323 s. Furthermore, the results were compared with the uniform porosity metal foam system, and deduced that the two-layer system did not always have the lower melting time compared with that of the uniform porosity system because it depended on the VFR and shape of the different porosities filled in the different layers. Additionally, for an average porosity of the metal foam, an optimal combination of two different porosities was observed for the melting performance.

A natural convection heat transfer inside rhombic square cavity partially filled with porous material have been numerically investigated. A constant heat flux has been applied to the left wall with a right wall kept in constant cold temperature while thermally insulated the top and bottom walls. Finite volume technique with Simple algorithm have been used to simulate the governing equations of fluid flow and heat transfer coupled with Darcy-Brinkman model to simulate the flow of the air inside the main cavity and the open cells of the porous media. Three factors were chosen to study their effects on the natural air velocity and the mechanism of the free convection inside the enclosure. The inclined angle of the sidewall of the rhombic (q = 90o, 80o and 70o), the thickness of the metal foam (t = 5 cm, 10 cm, and 15 cm) and the amount of heat flux (q = 150 to 600 w/m2). Copper metal foam with 0.9 porosity was chosen as porous media with open cell filled by air (Prandtl number =0.7) and 10 as pore density. The results showed that using a layer of porous metal foam with open cells will increase the heat transfer rate. It was 41.3% enhancement when use 5 cm of porous media and 68% for 15 cm. Acute inclined angle will decrease local Nusselt number and led to form vorticities. Furthermore, high heat flux increased the average Nusselt number and improved the heat transfer rate.

Abstract A solid substance encircled by a three-dimensional network of voids not interconnected with each other is referred to as close-cell metal foam. The work is based on enhancing mechanical properties of aluminum base close-cell metal foam through the addition of reinforcing particles in varying percentages. Closed-cell aluminum foams with the addition of Mn (0.5 wt.%) and Mg (0, 1, 1.5, 2) were successfully prepared by the melt route method. Al-based metal foam’s morphology and mechanical behavior were examined in order to understand the impact of reinforcing elements. From the current work, it is inferred that the addition of reinforcing elements initially helped to increase the compressive strength as found in Foam-1, but further addition of Mg did not have any beneficial effects. It was found that the value of compression strength depends on foam density. The addition of reinforcing elements increases the length of the plateau which in turn increases the value of energy absorption. It is found that proper bonding of reinforcing particles helps in improving energy absorption. From the evaluation, it was found that besides the increase in density and variations in pores uniformity, Al + Mn (0.5wt. %) + Mg (1.5wt. %) Foam (Foam-1) was found to be superior among all other foams. It can also be concluded that by fixing the percentage of Mn by 1 wt%, the best results can be obtained by addition of 1.5 wt. % Mg in the melt. Further addition of Mg shows a detrimental effect on mechanical and physical properties.

The aim of the present research work is to understand the intricacies of fluid flow through a rectangular channel that has been partially filled with a metal foam block of different blockage ratio (0.16-1), with a pore density (5–30 Pores Per Inch i.e. PPI), along with varying inlet velocity (6.5–12.5 m/s). For the porous region, numerical solutions are acquired using the Darcy Extended Forchheimer model. The Navier-Stokes equation is used in the non-porous zone. Different flow behaviours were seen as a function of PPI, height, and inlet velocity. The pressure drop increases with inlet velocity, PPI, and block height, with a maximum value of approximately 4.5 kPa for the case of 30 PPI, 12.5 m/s, and a blockage ratio of 1. Results show that the existence and location of the formation of eddies depends on the inlet velocity, PPI, and blockage ratio. Such studies have been reported less and will aid research on forced convection through a channel partially filled with metal foam and optimisation studies between increased heat transmission and the additional pressure drop for the same by providing a detailed fluid flow analysis.

The use of Phase Change Materials (PCMs) for latent thermal energy storage enhances the availability of solar energy. PCMs can store a large amount of energy in a small volume using almost entirely isothermal processes. Despite this, the poor thermal conductivity of PCMs is a significant disadvantage of current PCMs, severely limiting their energy storage capabilities. As a result, the solidification/melting rates are reduced to an unacceptable level, and the system reaction time is increased unreasonably. By combining the novel fin arrangement, nanoparticles, and metal foam, the current study improved the solidification rate of the PCM in the Latent Heat Thermal Energy Storage System (LHTESS). LHTESS was numerically evaluated in ANSYS Fluent 18.1 using a solidification and melting model. The addition of cesaro fins, nanoparticles, and metal foam significantly improved PCM solidification in the LHTESS. PCM solidification time was reduced by 42.42% and 39.39% in Type-3 and Type-5 fin configurations, respectively, when compared to Type-4 fin configuration. Furthermore, a temperature difference of 27 K between the Heat Thermal Fluid (HTF) and the PCM ensures the best solidification performance. By incorporating nanoparticles into PCM and metal foam, the solidification time is reduced by 73.68%. Depending on the foam structure and volume fraction of the nanoparticles, dispersing nanoparticles in PCM with metal foam saves up to 75% of the time.

In this work, theoretical and numerical studies of the dynamic response of a fiber–metal laminate (FML) sandwich beam under uniform blast loading are conducted. On the basis of a modified rigid-plastic material model, the analytical solutions for the maximum deflection and the structural response time of FML sandwich beams with metal foam core are obtained. Finite element analysis is carried out by using ABAQUS software, and the numerical simulations corroborate the analytical predictions effectively. The study further examines the impact of the metal volume fraction, the metal strength factor between the metal layer and the composite material layer, the foam strength factor of the metal foam core to the composite material layer, and the foam density factor on the structural response. Findings reveal that these parameters influence the dynamic response of fiber–metal laminate (FML) sandwich beams to varying degrees. The developed analytical model demonstrates its capability to accurately forecast the dynamic behavior of fiber–metal laminate (FML) sandwich beams under uniform blast loading. The theoretical model in this article is a simplified model and cannot consider details such as damage, debonding, and the influence of layer angles in experiments. It is necessary to establish a refined theoretical model that can consider the microstructure and failure of composite materials in the future.

Metallic foams exhibit unique properties that make them suitable for diverse engineering applications. Accurate mechanical characterization is essential for assessing their performance under both monotonic and cyclic loading conditions. However, despite the advancements, the understanding of cyclic load responses in metallic foams has been limited. This study aims to propose a mesostructural model to assess the fatigue behavior of open-cell metal foams subjected to cyclic loading conditions. The proposed model considers the previous load history and is based on the analogy of progressive collapse, integrating a finite element model, a fatigue analysis model, an equivalent number of cycles model, and a failure criterion model. Validation against experimental data shows that the proposed model can reliably predict the fatigue life of the metallic foams for specific strain amplitudes.

A solid substance encircled by a three-dimensional network of voids not interconnected with each other is referred to as close-cell metal foam. The work is based on enhancing mechanical properties of aluminum base close-cell metal foam through the addition of reinforcing particles in varying percentages. Closed-cell aluminum foams with the addition of Mn (0.5 wt.%) and Mg (0, 1, 1.5, 2) were successfully prepared by the melt route method. Al-based metal foam's morphology and mechanical behavior were examined in order to understand the impact of reinforcing elements. From the current work, it is inferred that the addition of reinforcing elements initially helped to increase the compressive strength as found in Foam-1, but further addition of Mg did not have any beneficial effects. It was found that the value of compression strength depends on foam density. The addition of reinforcing elements increases the length of the plateau which in turn increases the value of energy absorption. It is found that proper bonding of reinforcing particles helps in improving energy absorption. From the evaluation, it was found that besides the increase in density and variations in pores uniformity, Al + Mn (0.5wt. %) + Mg (1.5wt. %) Foam (Foam-1) was found to be superior among all other foams. It can also be concluded that by fixing the percentage of Mn by 1 wt%, the best results can be obtained by addition of 1.5 wt. % Mg in the melt. Further addition of Mg shows a detrimental effect on mechanical and physical properties. [ABSTRACT FROM AUTHOR]

Various researchers in the field of engineering have used porous media for many years. The present paper studies heat enhancement using two different types of porous media. In the first type, porous metal foam media was used experimentally and numerically for heat extraction. The porous medium was replaced with a porous structure using the Gyroid model and the triply periodic minimum surfaces technique in the second type. The Darcy–Brinkman model combined with the energy equation was used for the first type, whereas Navier–Stokes equations with the energy equation were implemented for the second type. The uniqueness of this approach was that it treated the Gyroid as a solid structure in the model. The two types were tested for different heat fluxes and different flow rates. A comparison between the experimental measurements and the numerical solution provided a good agreement. By comparing the performance of the two types of structure, the Gyroid structure outperformed the metal foam for heat extraction and uniformity of the temperature distribution. Despite an 18% increase in the pressure drop in the presence of the Gyroid structure, the performance evaluation criteria for the Gyroid are more significant when compared to metal foam. [ABSTRACT FROM AUTHOR]

Closed-cell aluminum foams have many excellent properties, such as low density, high specific strength, great energy absorption, good sound absorption, electromagnetic shielding, heat and flame insulation, etc. As a new kind of material, closed-cell aluminum foams have been used in lightweight structures, traffic collision protections, sound absorption walls, building decorations, and many other places. In this paper, the recent progress of closed-cell aluminum foams, on fabrication techniques, including the melt foaming method, gas injection foaming method, and powder metallurgy foaming method, and on processing techniques, including powder metallurgy foaming process, two-step foaming process, cast foaming process, gas injection foaming process, mold pressing process, and integral foaming process, are summarized. Properties and applications of closed-cell aluminum foams are discussed based on the mechanical properties and physical properties separately. Special focuses are made on the newly developed cast-forming process for complex 3D parts and the improvement of mechanical properties by the development of small pore size foam fabrication and modification of cell wall microstructures. [ABSTRACT FROM AUTHOR]

The development of energy storage systems has become crucial to reduce negative environmental impacts and overcome the mismatch between the required and produced energy. Thermal energy storage systems (TESS) have become highly relevant, and one of the most promising TESS systems is the latent heat thermal energy storage system (LHTESS) based on phase change materials (PCMs). However, the low thermal conductivity and poor heat transfer capabilities of PCMs limit their performance. The use of metal foams as porous media in LHTESS can enhance the low thermal conductivity of PCM and exploit its high energy density. The study performs a simulation on a vertical shell and convergent tube geometry composed of metal foam filled with pure paraffin wax as the PCM considering external heat losses and using the Darcy-Forchheimer model and the enthalpy-porosity theory to analyze the thermal behavior of the system. The numerical results show that the combination of metal foam with PCM significantly improves heat transfer, resulting in a much faster phase change process and reduced melting time. The study can also be expanded further to simulate other types of metal foam and PCMs. [ABSTRACT FROM AUTHOR]

• Homogenisation effects on the vibrations of mutlilayered microbeams with an AFG core and metal foam face layers are studied. • Differences in natural frequencies between homogenisation schemes vary with varying power gradation constant. • Higher length scale parameter leads to larger differences in natural frequencies between homogenisation schemes. • Relationship between the rotational natural frequency and the functionally graded core thickness is not linear. This study assesses the significance of homogenisation models in theoretically analysing the vibrations of three-layered microbeams with a core composed of axially functionally graded (AFG) material and with upper and lower face layers composed of metal foam material, especially when the third order shear deformation beam theory and the modified couple stress theory are used. The material of the core is assumed to vary following a power gradation profile. The range of homogenisation schemes, including the Voigt model, Reuss model, Voigt-Reuss-Hill model, Tamura model, Mori-Tanaka model, lower and upper bounds of Hashin-Shtrikman, and the local representative volume element (LRVE) model, are utilised to approximate the material properties of the AFG core. The upper and lower layers of metal foams are modelled using the closed-cell and open-cell solid porosity models. The coupled motion equations are solved for the natural frequencies of the system for the transverse, rotational and axial directions. A software-based finite element analysis (FEA) study of two simplified macrobeam systems was undertaken and the agreement between the FEA and numerical results, using the presented theoretical method, is found to be excellent. It has been confirmed that the homogenisation schemes have a notable effect on the mechanical properties of the AFG core, and hence on the coupled translational-rotational motion's natural frequencies. The largest difference in natural frequencies between different homogenisation schemes is found with a power gradation constant of approximately 0.53. A larger disparity of natural frequencies between different homogenisation methods was seen with an increase in the thickness of the AFG core and the microbeam's length-scale parameter of multilayered porous microbeam. The results of this study highlight the significance of homogenisation scheme employed when investigating the vibrations of a multilayered microbeam with an AFG core and metal foam porous face layers. [ABSTRACT FROM AUTHOR]

This paper deals with the separate electrochemical recovery of transition metals from battery black liquor. In a first approach, the authors investigated a model waste electrolyte mainly consisting of Cu, Co, Ni, and Mn in an acidic solvent, using citric acid as a complexing agent. An open porous Inconel® foam had been included as an electrode to benefit from the increased active surface area. Under the selected operation conditions, Cu was completely recovered, presenting almost 100% purity, while, in the case of Co, the purity was 96%, and a remanent concentration of about 1.2 g L−1 could still be determined. [ABSTRACT FROM AUTHOR]

The improvement in solar chimneys' thermal performance and thermal behavior that can be achieved by adding metal foam has been tested in computational work. The flow and heat transfer governing equations for solar chimney models were solved using computational fluid dynamics (CFD). It was solved using the control volume numerical method in ANSYS FLUENT 14.5. It is used to construct a finite volume modeling technique for solving the governing equations and the radiation heat transfer equations. With standard flat absorber plates, the results showed that heat transmission was increased by the inclusion of metal foam (10 PPI), leading to an increase in air velocity at the solar chimney of around 13.3%. The highest average air velocity with 10 PPI drops by 54.4% as the height of the absorber plate changes from 5 cm to 25 cm respectively.

Solar energy is a key player among other renewable energies that reduce greenhouse gases and replace conventional fuel, i.e., to solve global warming and fossil fuel descending issues. However, the thermal solar systems’ performance should be enhanced to cope with intermittent solar radiation. Metal foam can be used as an enhancer in solar collectors’ receivers. However, metal foams are associated with pressure drop. To benefit from the metal foam as a thermal enhancer and overcome the pressure drop issue, the present study numerically and experimentally investigates a novel Compound Parabolic Solar Collector (CPC) receiver with innovative uneven metal foam inserts of varying thickness. Two pores per inch (PPI) Cu-foam inserts, PPI10 and PPI20, were tested. These inserts were strategically placed at three different positions along the receiver, with thicknesses of 3 cm, 2 cm, and 1 cm starting from the inlet side. In the experimental part, three tubular receivers were tested, empty, i.e., without metal foam, inserted with Cu-foam of PPI10, and inserted with Cu-foam of PPI20. The experiments were conducted from 09:00 AM to 04:00 PM. The investigation involved water volume flow rates from 0.2 to 0.6 l/min. The numerical part included solving the governing equations, i.e., mass, momentum, and energy conservation, simulating conditions similar to the experiments. The Brinckman model described the fluid flow through the metal foam. The thermal performance of the CPC system was evaluated using the Nusselt number (Nu), thermal efficiency, water bulk temperature, and water outlet-inlet temperature difference. Inserting Cu-foam of PPI20 resulted in the hourly maximum Nu and thermal efficiency compared to the empty and PPI10 cases. Experimentally, the hourly maximum Nu was 8.9, 8.4, and 7.9 for PPI20, PPI10, and empty receivers, respectively, at 0.6 l/min. The average thermal efficiency was 88.3, 85, and 81.9 for PPI20, PPI10, and empty receivers, respectively, at 0.6 l/min. As for the outlet-inlet water temperature difference, the highest values were at 0.2 l/min. Again, PPI20 recorded the best results, i.e., 23.3 K, 21.5 K, and 20.2 K for PPI20, PPI10, and empty cases, respectively.

Foam metal as a promising application of explosion-proof and explosion-suppression materials, which itself has a complex three-dimensional pore structure, can be more effective in quenching gas and dust explosion flame in this research, a platform was created to experiment with dust deflagration using transparent quartz tubes and high-speed photography. The study focused on how copper foam affects flame propagation during deflagration of three kinds of dust: polyethylene, aluminum, and wheat. The results showed that copper foam hinders the flame front displacement and reduces fluctuations in flame propagation velocity when compared to deflagrations that do not have copper foam. However, placing copper foam too close to the ignition source can increase the magnitude of fluctuations in the early stages of the deflagration. When copper foam was placed 360 mm above the source of ignition, the 10PPI and 20PPI copper foam were able to decrease the flame of polyethylene dust and aluminum dust. As the porosity of the metal foam increases, the 30PPI copper foam can completely extinguish the flame of the three powders. The research also found that copper foam can divide the flame, quench the flame entering the copper foam, and block some of the burned and unburned powders, thereby reducing the energy of the deflagration and weakening the reaction. Comprehensively, to explore the inhibition effect of different parameters of copper foam against dust deflagration, which is of some significance for the study of fire and explosion control.

Porous copper (Cu), with varying porosities, has been made using carbamide as a space holder through the powder metallurgy route. Two shapes of carbamide particles were used, (i) needlelike and (ii) spherical, in order to investigate the effect of the space holder shape on the pore structure and mechanical properties of porous Cu. The compressive deformation behavior of porous Cu was studied under a compression test. The pores’ structural characteristics and mechanical properties of the porous Cu varied significantly with the shape of the space holder. Although the effect of the space holder shape on the porosity was not regular, the effect on the mechanical properties was regular. The stress increased monotonically with the increase in the strain, and strain hardening occurred at the plastic yield stage. The elastic modulus and yield strength followed the power law, with the relative density irrespective of the space holder shape. The empirical constants associated with different empirically developed power law relations were different, according to the shape of space holder. A quantitative relationship between the elastic modulus and yield strength and the spacer content was obtained to control the mechanical properties of the present porous Cu or other porous metals and metal foams using the well-known space holder method.

In this study, a novel design was proposed for enhancing heat transfer in a channel with metal foam, corrugated walls, and hybrid nanofluids. The numerical analysis of hybrid nanofluids (MWCNTs+TiO2) with DW (distillate water) as the base fluid was performed in a channel with triangular corrugations and open metal foam. The mass fractions of hybrid nanofluids (mixture of DW and MWCNTs+TiO2) were set at 0.025%, 0.05%, and 0.075%. The effects of metal foam porosity and PPI (pore density), as well as different Reynolds numbers (ranging from 7000 to 13000), on thermal performance were investigated. The results showed that the heat transfer enhancement with metal foam increased by 130% for all hybrid nanofluids. Moreover, the heat transfer enhancement in metal foam with a porosity of 0.9 was 9.8% higher than that of metal foam with a porosity of 0.99. Additionally, quadratic correlations for the average Nusselt number (Nua) were proposed for all hybrid nanofluids, taking into account PPI, porosity, and Reynolds numbers as variables. Finally, the optimum values of Nua for all hybrid nanofluids were determined, providing valuable insights for optimizing the heat transfer performance in this configuration.

Photovoltaic cooling has become important in order to reduce the operating temperature and increase the electrical generation, efficiency, and useable time. The extract heat produced by this cooling process could either be used immediately or stored for later use. In this study, many goals were examined through experimental and numerical investigation. They included the effect of cooling the photovoltaic panels and the potential to use the heat removed by the PV cooling system as well as how to store it in a thermal energy storage box (TESB). This box, made of paraffin wax as a phase change material and supported by stainless steel foam, has been installed into a test wall for heating at later time. The test wall was a component of an insulated test room that was linked to the cooling systems of the photovoltaic panel, to be the integrated system. According to the study, there is plenty of potential for storing the heat energy that the PV cooling system removes and using it later from the thermal energy storage box. After using the integrated system, the mean useful energy increased by 83% from 39.2 W for the uncooled PV panel to 71.7 W for the integrated system. The maximum PV electrical generated outputs for uncooled and water-cooled panels were 40.9 W and 43.3 W, respectively. The efficiency of uncooled and water cooled PV panels was 14.2% and 14.7%, respectively and dramatically increased to 25.9% for the integrated system.

The surging interest in porous lightweight structures has been witnessed in recent years to pursue material innovations in broad engineering disciplines for sustainable developments and multifunctional proposes. Functionally graded (FG) porous composites represent a novel way to adjust mechanical characteristics by controlling the porosity distributions. However, the further advance in this field is challenged by the scale gap between mesoscopic and macroscopic aspects of porous structural analysis, i.e. how the local cellular morphologies impact the overall behaviors. The purpose of this paper is to bridge this gap by conducting a theoretical investigation on the performance of inclined self-weight sandwich beams with FG porous cores, where Young's modulus is obtained with representative volume elements (RVEs) in a multiscale modeling study and depends on the cellular morphologies: average cell size and cell wall thickness. The material properties of closed-cell steel foams are adopted in a two-step assessment on target beams, including a static calculation to examine their bending deformations under gravitational loading which are then imported into a forced vibration analysis considering constant and harmonic moving forces. Timoshenko beam theory is used to establish the displacement field, while Ritz and Newmark methods are employed to solve the governing equations in terms of bending, free vibration, and forced vibration. The inclined beams are assumed to rest on a Pasternak foundation, and the corresponding structural responses can be determined based on the specific cell size and cell wall thickness, of which the effects are quantitatively revealed: the stiffness degradation induced from cellular morphologies increases the dynamic deflections, while the corresponding self-weight static deformations are reduced and the fundamental natural frequencies are raised. The influence from geometrical, boundary, and foundation conditions is also discussed to provide a comprehensive overview. This will be valuable for engineers to develop devisable foam-based load-carrying components with enhanced properties. [ABSTRACT FROM AUTHOR]

Metal foams, which are similar to other types of foam materials, are composed of solid material with a significant proportion of the volume consisting of pores. Although metal foams retain some of the properties of the original material, they also possess several advantageous characteristics such as low density and thermal conductivity, high specific stiffness, and porosity. As a result, metal foams are becoming increasingly popular for applications such as heat exchangers, soundproofing devices, and gas–liquid filters. Additive manufacturing has the potential to expand the production capabilities of foams by reducing materials consumption and the creation of complex geometry. This work demonstrates the possibility of direct 3D printing of metal foams made of titanium, aluminum, and aluminum-bronze using direct energy deposition and special parameters of the printing process. This method is superior to traditional methods in terms of cost and the absence of additional stages of preparation and post-processing. The open porosity of the foam can be easily changed by varying the laser power. The laser power in the range of 10 to 180 W along with rapid prototyping makes it possible to obtain metal foams of complex geometry with a high degree of open porosity (up to 50% for titanium and up to 30% for aluminum alloys), not inferior in quality to foams obtained by conventional methods. Moreover, by changing the printing modes, it is possible to adjust the structure of foam from uniform to columnar, increasing the thermal conductivity and insulating properties of the samples. [ABSTRACT FROM AUTHOR]

Thermal management devices such as heat exchangers and heat pipes are integral to safe and efficient performance in multiple engineering applications, including lithium-ion batteries, electric vehicles, electronics, and renewable energy. However, the functional designs of these devices have until now been created around conventional manufacturing constraints, and thermal performance has plateaued as a result. While 3D printing offers the design freedom to address these limitations, there has been a notable lack in high thermal conductivity materials beyond aluminium alloys. Recently, the 3D printing of pure copper to sufficiently high densities has finally taken off, due to the emergence of commercial-grade printers which are now equipped with 1 kW high-power lasers or short-wavelength lasers. Although the capabilities of these new systems appear ideal for processing pure copper as a bulk material, the performance of advanced thermal management devices are strongly dependent on topology-optimised filigree structures, which can require a very different processing window. Hence, this article presents a broad overview of the state-of-the-art in various additive manufacturing technologies used to fabricate pure copper functional filigree geometries comprising thin walls, lattice structures, and porous foams, and identifies opportunities for future developments in the 3D printing of pure copper for advanced thermal management devices. [ABSTRACT FROM AUTHOR]

A semi-solid route is expected to be a fabrication method that can fabricate aluminum alloy foams with a variety of mechanical properties, but the allowance fluctuation of the fabrication conditions of aluminum alloy foams with high reproducibility is not clear. The objective of this study was to reveal the allowance fluctuation between the setting temperature and the actual temperature of the melt to fabricate stable foams, having pores with small pores and high circularity, and the influence of the increasing volume fraction of the solid on the pore morphology. Al-Si alloy foams were fabricated five times by adding a blowing agent into a semi-solid slurry under the same setting fabrication conditions, such as the temperature and concentration of oxygen in the atmosphere. The results of small relative standard deviations of pore diameter and circularity indicated that the conducted fabrication process had high reproducibility, even if the volume fraction of the solid changed in a range of 5%. When the volume fraction of the solid exceeds the minimal fraction of primary crystals for prevention of drainage, the clogging effect works more efficiently because the ratio of clogged cell walls increases. Additionally, the preferred range of the volume fraction of the solid for the fabrication of stable foam was revealed to be around 15% to 35%. [ABSTRACT FROM AUTHOR]

The improvement in solar chimneys' thermal performance and thermal behavior that can be achieved by adding metal foam has been tested in computational work. The flow and heat transfer governing equations for solar chimney models were solved using computational fluid dynamics (CFD). It was solved using the control volume numerical method in ANSYS FLUENT 14.5. It is used to construct a finite volume modeling technique for solving the governing equations and the radiation heat transfer equations. With standard flat absorber plates, the results showed that heat transmission was increased by the inclusion of metal foam (10 PPI), leading to an increase in air velocity at the solar chimney of around 13.3%. The highest average air velocity with 10 PPI drops by 54.4% as the height of the absorber plate changes from 5 cm to 25 cm respectively. [ABSTRACT FROM AUTHOR]

Forced convection heat transfer in metal foam pipe under uniform heat flux was investigated numerically. Water has been used as the fluid medium in numerical simulations with copper metal foam. The test sample used metal foam for four cases (A, B, C, and D) by using varying thicknesses of foam along the pipe. In case (A), the pipe was completely filled with metal foam; in case (B), the pipe was partially embedded with metal foam and close to the wall; in case (C), the pipe was partially filled in the section's center; and in case (D), the pipe was partially filled in the form of three sections along the pipe. The foam employed in this study has a porosity of 0.90 and pore density ranges from (10–40) PPI. The fluid and energy transfers are simulated using the Forchheimer-extended Darcy equation and the local thermal non-equilibrium (LTNE) model. The simulation is performed using the commercial software FLUENT with specific boundary conditions. Turbulence was taken into account using the k- ε model. The results reveal that when the pipe is filled partially with metallic foam as indicated in case B, the Nusselt ratio rises due to the velocity gradient and temperature distribution is more homogenous inside the pipe led to enhancement in overall heat transfer. Also, the metallic foam 40PPI has a highly Nusselt number ratio, with a big value equal to 5.5 in case B due to the highly conductive surface area of heat transfer from the wall heated to the fluid. Additionally, the pipe in case A was completely filled with metallic foam, resulting in a bigger pressure drop than in the other cases, which increases flow resistance. The metal foam in case C, which is centered in the pipe's center, has the lowest pressure drop measurement. The 10PPI metallic foam exhibits the highest performance factor when compared to other metallic foam.

A convective stability analysis of the flow in a vertical fluid-saturated porous slab made of two layers with different thermophysical properties is presented. The external boundaries are isothermal with one of them impermeable while the other is open to an external fluid reservoir. This study is a development of previous investigations on the onset of thermal instability in a vertical heterogeneous porous slab where the heterogeneity may be either continuous or piecewise as determined by a multilayer structure. The aim of this paper is investigating whether a two-layer structure of the porous slab may lead to the onset of cellular convection patterns. The linear stability analysis is carried out under the assumption that one porous layer has a thermal conductivity much higher than the other layer. This assumption may be justified for the model of a heat transfer enhancement system involving a saturated metal foam. A flow model for the natural convection based on Darcy's momentum transfer in a porous medium is adopted. The buoyancy-induced basic flow state is evaluated analytically. Small-amplitude two-dimensional perturbations of the basic state are introduced, thus leading to a linear set of governing equations for the disturbances. A normal mode analysis allows one to formulate the stability eigenvalue problem. The numerical solution of the stability eigenvalue problem provides the onset conditions for the thermal instability. Moreover, the results evidence that the permeability ratio of the two layers is a key parameter for the critical conditions of the instability. [ABSTRACT FROM AUTHOR]

Microelectronic components are used in a variety of applications that range from processing units to smart devices. These components are prone to malfunctions at high temperatures exceeding 373 K in the form of heat dissipation. To resolve this issue, in microelectronic components, a cooling system is required. This issue can be better dealt with by using a combination of metal foam, heat sinks, and nanofluids. This study investigates the effect of using a rectangular-finned heat sink integrated with metal foam between the fins, and different water-based nanofluids as the working fluid for cooling purposes. A 3D numerical model of the metal foam with a BCC-unit cell structure is used. Various parameters are analyzed: temperature, pressure drop, overall heat transfer coefficient, Nusselt number, and flow rate. Fluid flows through the metal foam in a turbulent flow with a Reynold's number ranging from 2100 to 6500. The optimum fin height, thickness, spacing, and base thickness for the heat sink are analyzed, and for the metal foam, the material, porosity, and pore density are investigated. In addition, the volume fraction, nanoparticle material, and flow rate for the nanofluid is obtained. The results showed that the use of metal foam enhanced the thermal performance of the heat sink, and nanofluids provided better thermal management than pure water. For both cases, a higher Nusselt number, overall heat transfer coefficient, and better temperature reduction is achieved. CuO nanofluid and high-porosity low-pore-density metal foam provided the optimum results, namely a base temperature of 314 K, compared to 341 K, with a pressure drop of 130 Pa. A trade-off was achieved between the temperature reduction and pumping power, as higher concentrations of nanofluid provided better thermal management and resulted in a large pressure drop. [ABSTRACT FROM AUTHOR]

In this work, turbulent forced convection heat transfer in a circular horizontal pipe with insert of metal foam under the condition of constant heat flux is experimentally investigated. The Nusselt number (Nu) and friction factor (f) were tested under heat flux (31.8 and 42.4) KW/m² and water flow rates (3, 6 and 9) lit/min. Circular copper pipe with dimensions of 0.6 m in length, 0.025 m in diameter, and 0.001 m in thickness acts as the test section for the current investigation. It is heated by an electric heater mounted outside the pipe. The foam has pores per inch ranging from (10 to 40) PPI and porosity between (0.89 and 0.93). The water flowing through the pipe has a regular input temperature of 32°C. The temperature was measured along the pipe distributed in seven sections of the wall, in addition to measuring the temperature of entering and exiting the water from the pipe. The results show that, with a heat flux of 42.4 KW/m², the copper metal foam of 40 PPI gives a higher increase in average Nusselt number up to 73% as compared to metal foam of 10 PPI of 63.74%. The difference in pressure drop between pipes with and without metal foam varies just slightly at 10 PPI, but becomes greater at 40 PPI. [ABSTRACT FROM AUTHOR]

In this study, three open-cell Zn (Al-Mg) alloy foams with two different pore sizes were prepared by an infiltration process that employs CaCl2 granules as space holders. The porosity of the three Zn alloy foams prepared by this method was in the range of 65–70%. The macrostructure and microstructure of the three foams were characterized systematically. Zn-5Al alloy foams showed a two-phase structure, mainly including the α-Al phase and η-Zn phase. The Zn-1.5Mg alloy foam consists of the η-Zn, Mg2Zn11 phase and MgZn2 phase. The Zn-3Al-1Mg alloy foam contains the η-Zn phase, α-Al phase, Mg2Zn11 phase and Mg2Al3 phase. The compressive properties of three kinds of foams were conducted to investigate the stress–strain behaviours. The compressive strength of the as-cast alloy foam with a large pore size reached 16-20 MPa, which was higher than that of the as-cast alloy foam with a small pore size (11-14 MPa). After homogenization, the peak stress of the three alloy foams with large pore sizes increased to 18-27 MPa, especially for the Zn-1.5Mg alloy and Zn-3Al-1Mg alloy foams. The corrosion resistance and corrosion mechanism of the three Zn alloy foams were studied by immersion corrosion experiments in simulated body fluid. The corrosion rates of the three Zn alloy foams with small pore sizes at the initial stage of corrosion were higher than those of foams with large pore sizes. The maximum initial corrosion rate was 11.720 mm/year for the Zn-3Al-1Mg alloy foam with a small pore size, followed by 5.983 mm/year for the Zn-1.5Mg alloy foam. The lowest corrosion rate was 0.811 mm/year for the Zn-5Al alloy foam with a large pore size. The corrosion rate decreased with immersion time and remained stable. In addition, the galvanic corrosion effect was observed in the three alloy foams by corrosion morphology analysis. The α-Al phase and Mg2Zn11 phase were corroded prior to the η-Zn phase. [ABSTRACT FROM AUTHOR]

Latent heat thermal storage (LHTS) system is vital to reduce environment pollution. In the shell-and-tube heat accumulator, the position of the inner heating tube plays a vital role in the thermal storage. To analyze the effect of the inner tube position on the phase transition, a two-dimensional numerical model is developed. The structure has the minimum full melting time of 3480 s when the inner tube is 12 mm (L = 12 mm) from the center. Compared with L = 0 mm, the full melting time at L = 12 mm can be reduced by 13.4%.

The performance of an electronic radiator filled with metal foam with a porosity of 96% was studied. The effect of the factors including the flow rates, the pores per linear inch (PPI) and the numbers of fins was analyzed. The results show that the electronic radiator with metal foam reflects a stronger ability of the heat transfer compared to the electronic radiator without metal foam. With the increase in the flow rate between 10 L/h and 60 L/h, the heat transfer coefficient of both of the two electronic radiators will be improved, but it is also dependent on the number of fins. In this study, we find that the heat transfer coefficient first increases and then decreases with the number of fins. The optimum number is three. As for the effect of the PPI, the higher the PPI, the larger the heat transfer coefficient, while the pressure drop always increases with the flow rates' increase, the pores per linear inch (PPI) and the numbers of fins. [ABSTRACT FROM AUTHOR]

Nowadays, foam structures have several applications in industries. Basically, discontinuities such as pores cause complications in evaluating the mechanical and fracture behavior. In other words, understanding the multi scale of porous cells in cracked foams can play a significant role in fracture prediction. The present research proposes an analytical approach based on the experimental concept of damage in which the behavior of cracked metal foam was investigated under mixed-mode I/III (tensile and out-of-plane) fracture. In this method, pores in foam are modeled as circular and elliptical defects. In this context, mechanical properties and crack inclination angle are obtained based on loading and configuration of pores. Dispersion of circular and elliptical discontinuities determines the overall modulus and crack inclination angle trajectory based on the experimental results, pure mode I SIF were occurred on (0°) and pure mode III were obtained at (62°) loading angle. The aluminum foams were produced and prepared according to the edge notch disc bend (ENDB) test method to obtain the onset of fracture initiation (K Ic and K IIIc) and trajectory of cracked foam body. The results demonstrated that analytical approach, based on circular pore distribution, had a good agreement with experimental results. Moreover, the results indicated that SIF in mode I and mode III had the most agreement with the experimental results at angles of 0° and 62°, respectively. [ABSTRACT FROM AUTHOR]

The era of considering carbon dioxide (CO2) as a waste stream has passed. New methods of utilising CO2 as a carbon feedstock are currently the focus of extensive research efforts. A fixed-bed reactor containing a commercial Cu/ZnO/Al2O3 catalyst washcoated on a Cu foam was used for the synthesis of methanol through direct CO2 hydrogenation. Catalytic activity tests in this reactor were conducted at reaction pressures of 30 and 50 bar, temperatures in the range 190–250 °C, and weight hourly space velocities (WHSV) in the range 1.125–2.925 NL gcat−1 h−1. The best reactor performance was recorded at 50 bar pressure: CO2 conversion and methanol selectivity of 27.46% and 82.97%, respectively, were obtained at 240 °C and 1.125 NL gcat−1 h−1. Increasing the WHSV to 2.925 NL gcat−1 h−1 resulted in a twofold increase in methanol weight time yield (WTY) to 0.18 gMeOH gcat−1 h−1 and a decrease in methanol selectivity to 70.55%. The results presented in this investigation provide insight into the performance of a bench-scale reactor in which mass transfer limitations are non-negligible and demonstrate that metal foams are promising catalyst support structures for CO2 hydrogenation towards methanol production. [ABSTRACT FROM AUTHOR]

The article presents alternative metal-supported catalysts for decomposition of the highest-class hydrogen peroxide: 98%+ (Type 98 HP, according to MIL-PRF-16005F). The aim of this study was the experimental investigation of an alternative solution for decomposition of 98%+ hydrogen peroxide, strictly for chemical propulsion. High-porosity open cell metal foams have been identified as structures with great potential. Low density, good mechanical and thermal properties, availability of various materials and alloys as well as new technologies of manufacturing, make metal foam a potential solution for many different propellants, not only hydrogen peroxide. Open cell NiCrAl foam has been processed to prepare several catalysts, with different content and dispersion of the active phase. Cleaning and drying were performed to prepare carriers for further processing: wet impregnation, slow drying, and calcination. Simple drop tests with 98% hydrogen peroxide have been conducted to estimate activity level of catalysts, in a simplified scale: low, medium, high. Then, real-environment tests have been performed in a catalyst bed. Temperature, pressure along the bed and propellant mass flow rate were measured while testing. The analysis of the test results provided a general conclusion that metal foam supported manganese oxide catalyst is a promising solution for hydrogen peroxide propulsion. [ABSTRACT FROM AUTHOR]